Moshe (Moses) is taught the laws of the Red Heifer, whose ashes purify a person who has been contaminated by contact with a dead body.

After 40 years of journeying through the desert, the people of Israel arrive in the wilderness of Zin. Miriam dies and the people thirst for water. G-d tells Moses to speak to a rock and command it to give water. Moses gets angry at the rebellious Israelites and strikes the stone. Water issues forth, but Moses is told by G-d that neither he nor Aharon (Aaron) will enter the Promised Land.

Aharon dies at Har Hahar and is succeeded in the High Priesthood by his son Elazar. Venomous snakes attack the Israelite camp after yet another eruption of discontent in which the people "speak against G-d and Moshe "; G-d tells Moshe to place a brass serpent upon a high pole, and all who will gaze heavenward will be healed. The people sing a song in honor of the miraculous well that provided the water in the desert.

Moshe leads the people in battles against the Emorite kings Sichon and Og (who seek to prevent Israel's passage through their territory) and conquers their lands, which lie east of the Jordan.